Instrumentation: Heavy metal content in all the filtrates was quantified using Inductively Coupled Plasma-optical emission spectroscopy (ICP-OES; Perkin Elmer Optima-3300 RL). The amount of metal sorbed at equilibrium, q (mg g-1), which represents the heavy metal uptake was calculated from the difference in metal concentration in the aqueous phase before and after adsorption according to Basha et al. (2006).
Adsorption isotherms: Adsorption from aqueous solutions at equilibrium is usually correlated by Freundlich and Langmuir isotherm (Freundlich, 1907).